1. Field of the Invention
This invention relates to sludge collectors for removing sludge from rectangular settling tanks and, more particularly, to a sludge collector flight.
2. Description of Related Art
Sludge collectors are commonly used in waste water treatment plants to scrape the settled sludge from the bottom of the settling tank and also to skim floating waste off the surface of the waste water. These sludge collectors typically include a number of sludge flights, which are usually elongated members that extend the width of the tank. The ends of the flights are connected to conveyor chains, which carry the flights in a circuit lengthwise along the bottom of the tank and back over the surface of the water to perform the scraping and skimming functions. The ends of the flights are supported at the surface of the water by support rail assemblies, or tracks, which are fastened to the longitudinal sidewalls of the settling tank. The length of the flights between the chains is unsupported, and in typical settling tanks having widths of twenty feet or more, the flights are subjected to substantial bending forces from the scraping and skimming operations.
The settling tank itself is usually made of concrete and rails are embedded in the bottom of the settling tank to provide a track along which the flights are transported during the scraping operation. The portions of the flights which engage the rails during the scraping operation and also the portions of the rails that engage the support rail assemblies during the skimming operation are subject to wear. Therefore, wear shoes are typically attached to the flights at these portions to protect the flights. Prior art wear shoes are constructed of metal or plastic and are connected to the flights with several fasteners. However, the fasteners are subject to corrosion from exposure to the waste water, making removal of the wear shoes difficult. The fasteners must often be cut. This makes replacing the wear shoes timely and labor intensive.